BAGHDAD — Iraq's Cabinet will vote Sunday on a security pact with Washington that would keep U.S. forces in the country for another three years, a major step in efforts to balance Iraqi demands for national sovereignty with the security concerns of the two allies.

In a bid to secure support for the agreement from the country's top Shiite cleric, Prime Minister Nouri al-Maliki on Saturday dispatched two senior lawmakers to see Grand Ayatollah Ali al-Sistani in the holy city of Najaf, south of Baghdad.

Al-Sistani commands enormous influence with Iraq's majority Shiites and has the power to sink the agreement or help it through the vote in the Cabinet, and if approved, in a subsequent vote in parliament. There was no word on where he stands, but the two politicians were upbeat after their 90-minute meeting with him.

The U.N. mandate covering the presence of U.S. and other foreign forces in Iraq expires Dec. 31, and failure to pass the agreement would leave Iraq with little choice but to seek a renewal of the mandate.

A series of bombings Saturday pointed to the fragility of security gains in the past year. The violence also was likely to strengthen the argument of the pact's proponents, including the interior and defense ministers, that there is still a need for U.S. forces.

In Tal Afar, a suicide car bombing struck a commercial district, killing 10 people and wounding 20, according to the U.S. military. Iraqi police and hospital officials said seven people were killed and up to 32 were wounded. There was no immediate explanation for the discrepancy.

In Baghdad, a bomb in a parked car exploded near the National Theater in the mainly Shiite district of Karradah, killing at least five and wounding 23, according to police and hospital officials. Some victims were heading to the theater to see a political satire, said the officials, speaking on condition of anonymity because they were not authorized to release the information.

The U.S. military, however, said initial reports indicated no deaths but 19 civilians wounded in the Baghdad bombing. It also said a suicide bomber in a vehicle in the northern city of Mosul injured 13 Iraqis on Saturday, and that a U.S. Marine died from wounds suffered in a roadside bombing west of Baghdad on Friday.

Also Saturday, two American soldiers died when a helicopter made a "hard landing" after hitting wires in Mosul, the U.S. military said.

Mosul is a flashpoint of insurgent activity that has defied stepped up efforts by U.S. and Iraqi forces to bring stability. The attacks Saturday raise questions about the preparedness of Iraqi forces and back assertions by proponents of the security pact that they still need American help.

'Good chance' of passageA close aide to al-Maliki and two Cabinet ministers said Iraqi and U.S. negotiators have agreed on a final draft of the security pact with the United States and that it would be put to a vote in an emergency Cabinet meeting Sunday.

The aide, speaking on condition of anonymity because of the sensitivity of the subject, said the pact stood "a good chance" of being passed by a two-thirds majority in the 37-member Cabinet and that the final draft was reached after "intense" contacts between the American and Iraqi sides.

In Washington, National Security Council spokesman Gordon Johndroe described the final document as beneficial to the allied nations.

"We think this is a good document that serves both Iraqis and Americans well," he said. "We remain hopeful that the Iraqi government will conclude this process soon."

Khalid al-Attiyah, one of the Shiite lawmakers who met al-Sistani on Saturday, told reporters in Najaf that the Americans have agreed to two changes proposed by al-Maliki. One of the two, he said, removed a phrase that could delay the withdrawal of U.S. forces from Iraqi cities and back to bases in outlying areas by the end of June.

He did not mention the second change. Iraq has demanded guarantees for its right to try U.S. soldiers and defense contractors for serious crimes committed off-duty and off-base and to ensure that the United States does not use Iraqi territory to attack a neighboring country, such as Iran or Syria.

It also wanted stronger language to clarify that U.S. troops cannot stay in Iraq after Dec. 31, 2011.

Parties fear political backlashIf the Cabinet passes the draft agreement Sunday, the 275-seat parliament could follow suit because the political blocs in al-Maliki's government dominate the legislature. The agreement needs a simple majority to pass in parliament.

The final step would be ratification of the deal by President Jalal Talabani and his two vice presidents. The three met Saturday to review the final version of the agreement, according to Talabani's office.

Most political parties have been reluctant to state their position on the pact, fearing a voter backlash in key provincial and general elections in 2009 and the stigma of being seen as condoning the presence in Iraq of U.S. forces who are viewed as an occupation army.

Some, including al-Maliki's senior partner in the government, looked to al-Sistani for political cover, saying they would only sign off on the agreement if the cleric backed it. Shiite leader Muqtada al-Sadr, whose militiamen fought U.S. forces in three uprisings since 2003, has threatened to renew attacks on the Americans if they don't immediately begin to withdraw from Iraq.

The only major group that supported the pact from the start was the Kurdish bloc, America's most reliable ally in Iraq. The Kurds look to Washington as the guarantor of their self-ruling enclave in northern Iraq.